Trigger updating same table oracle

During table opening the server loads triggers assigned to the table from the data dictionary into the main memory.

Triggers are loaded in the order defined by the field ‘triggers’ in the file ‘. For every trigger being loaded the server assigns the value to ACTION_ORDER attribute that is one greater than the ACTION_ORDER value of trigger loaded before (if any). Later when a user creates a new trigger issuing the statement ‘CERATE TRIGGER …’ the server assigns the value to attribute ACTION_ORDER based on the value of this attribute already assigned to table triggers for the same action/timing pair.

Implementation of triggers support was significantly refactored during adding support for multiple triggers per table for the same action/timing.

The figure below depicts the major classes involved in support of triggers in My SQL server.

Include PRINT statements in your triggers so that you can determine where the failure has occurred.

USE Adventure Works2012; GO -- Turn recursive triggers ON in the database. CREATE TRIGGER dbo.emp_mgrupd ON dbo.emp_mgr FOR UPDATE AS IF UPDATE (mgr) BEGIN UPDATE dbo.emp_mgr SET emp_mgr. No Of Reports 1 -- Increment mgr's FROM inserted -- (no. No Of Reports - 1 -- Decrement mgr's FROM deleted -- (no.

That is, if user executes the following statements: ACTION_ORDER values are used by server to control the order of trigger execution.

Server executes triggers in the ascending order of ACTION_ORDER values.

You can use nested triggers to perform useful housekeeping functions such as storing a backup copy of rows affected by a previous trigger.

For example, you can create a trigger on Note Because triggers execute within a transaction, a failure at any level of a set of nested triggers cancels the entire transaction, and all data modifications are rolled back.

And this triggers will be called in the prescribed order determined (in generally) by the sequence in which triggers were created.

In the implementation of multiple triggers per table the main point was the order of triggers execution.

In result of every step described before there is an object TABLE that points to an object Table_trigger_dispatcher.

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